From: mathew <meta@...>
Date: 2005-07-19T23:21:00+09:00
Subject: Re: FTP problems on windows

csjasnoch@wisc.edu wrote:
> When I run from a Mac OSX machine I can access fine, but from the
> windows machines I am getting "Net:FTPTempError 425 Can't Open Data
> Connection"

It's probably a firewall on the Windows machine.

FTP is a multi-connection protocol. When you ask it to transfer a file, 
it opens a second TCP/IP connection on a random port, and uses that to 
transfer the data. Obviously this is a problem when the two machines are 
behind firewalls.

You can choose which machine initiates the connection via a choice of 
passive FTP vs regular FTP. However, that just chooses who has to open 
their firewall--either way there's still a random-port connection to 
deal with.

That's in general; in the case of the Ruby library, I don't recall 
seeing any option for passive FTP. So in this case, the server is 
picking a random port > 1024, and trying to open a connection on that 
port to the client code.

> I am not exactly sure how to deal with this.

Don't use FTP unless you have to. It's a really lousy protocol.

Probably the Mac is handling it because it doesn't have quite as severe 
a firewall as the Windows box (because Macs don't have the same degree 
of security problems as Windows boxes).


mathew
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